POSTPRANDIAL HYDROGEN BREATH EXCRETION, PLASMA LACTATE CONCENTRATION,GLUCOSE-METABOLISM AND INSULIN LEVELS IN VEAL CALVES

Veal calves intensively fed with milk replacers towards the end of fat tening often develop hyperglycaemia, glucosuria, hyperinsulinaemia and insulin resistance. Experiments were designed to study hydrogen exhal ation, plasma lactate concentrations, glucose metabolism, insulin conc entrations and gas exchange for 5 h after milk replacer intake in veal calves at the age of 3.5 months with a mean weight of 151 kg. [6,6(2) D]-glucose was intravenously infused from 2 h before to 5 h after feed ing to study glucose metabolism. Hydrogen exhalation started to increa se (p < 0.05) after 120 min, while plasma lactate, glucose and insulin increased (p < 0.01) within 15-30 min and reached peak levels at 180, 90 and 90 min, respectively, after intake of milk replacer, whereas t he respiratory exchange ratio was nor. significantly altered. [6,6(2)D ]-glucose atom excess decreased (p < 0.05) within 60 min after the mea l to a new steady state. Based on H-2 exhalation data a marked microbi al breakdown of ingested nutrients (and probably especially of lactose ) starred more than 2 h after the meal. The postprandial rise of plasm a L-lactate was probably the result of enhanced metabolization of abso rbed glucose. The decrease of [6,6(2)D]-glucose atom excess data withi n the first 60 min after the meal demonstrate that enhanced (and proba bly insulin-mediated) glucose utilization was maintained throughout th e 5-h study, but was not further increased 1 h after the meal. Because the respiratory exchange ratio was not significantly altered, glucose oxidation did not seem to make a major contribution to glucose utiliz ation.